1. Field
Embodiments of the present invention generally relate to apparatus and method for processing semiconductor substrates. Particularly, embodiments of the present invention relate to apparatus and methods for rapid thermal processing.
2. Description of the Related Art
Rapid thermal processing (RTP) is a process for annealing substrates during semiconductor processing. During RTP, a substrate is generally supported by a supporting device near the edge region and rotated as the substrate is heated by one or more heat sources. During RTP, thermal radiation is generally used to rapidly heat a substrate in a controlled environment to a maximum temperature of up to about 1350 degrees Celsius. Incandescent halogen lamps are often used as thermal radiation source during RTP. Incandescent halogen lamps are usually packed side by side in an array for generate high density and relatively uniform radiant power.
However, there are limitations in using incandescent lamps as radiant source for RTP. First, the density of the radiant energy generated by incandescent halogen lamps is limited by the density of packing which is inherently limited by the size of the halogen lamps. Second, the maximum temperature of the incandescent halogen lamps is also limited by the maximum temperature of the filament in each incandescent lamp. For example, the maximum temperature can be emitted by the filament of an incandescent lamp is less than about 3000 Kelvin (2730 degrees Celsius). Next, thermal inertia of the filaments in the incandescent lamps also limits the rates of temperature ramp up and ramp down, thus, limits throughput.
Furthermore, because incandescent lamps radiant in all redirections, it is difficult to control the amount of energy directed towards the substrate being processed. Additionally, the array of incandescent lamps generally covers the entire surface of the substrate during processing making it difficult to have a clear line of sight of the substrate for monitoring, such as measuring a substrate temperature with a pyrometer.
Therefore, there is a need for apparatus and methods for rapid thermal processing with improved radiant source.